The present invention generally relates to a wheel with variable compliance having many applications, including ground vehicle wheels, printing press rollers, material processing and handling equipment. More particularly, the present invention relates to a wheel that includes a rim having a center axis of rotation and a plurality of wheel segments engaged with the rim and connecting to a radial band appropriate for the intended usage of the wheel, where the rim and plurality of wheel segments are adapted to rotate about the center axis, and where the attachment points to the rim of the plurality of wheel segments can be moved in the direction of the axis of rotation. In the example of a ground vehicle application, the radial band includes tread elements to improve vehicle traction in wet or rough road surfaces or in complex terrain. For material handling applications, the radial band may have a smooth surface to apply even pressure to a printing medium, for example, or may contain striations or tread elements as required.
Various mechanisms currently exist for varying the ground contact pressure of a tire while a vehicle is being driven. This capability allows a vehicle to traverse soft soils by lowering the pressure within the tire, without compromising on-road performance. This is commonly achieved by varying the pressure within the carcass of a tire through the control of an air valve mounted on the wheel that can vent the tire's internal air to atmospheric pressure or to the pressure produced by an onboard air compressor plumbed through an airtight rotary seal. The commercial term for such a system is Central Tire Inflation System (CTIS). One such system is U.S. Pat. No. 5,553,647, “Central tire inflation system,” (Miroslav), the contents of which are hereby incorporated by reference, that describes a pressure air source, plumbing, valve, pressure sensor, and control system for varying the internal air pressure of a tire while driving. The shortcomings of this design are complexity, sensitivity to the elements, cost, and inability of the system to maintain adequate tire pressure when the tire is badly damaged.
Several patents have addressed this latter concern of pneumatic tire vulnerability with runflat inserts (U.S. Pat. No. 6,263,935, “Radial ply pneumatic runflat tire,” (Oare, et. al.)) or tires that do not rely on fluidic pressure for load carrying, a.k.a. non-pneumatic tires, (U.S. Pat. No. 6,431,235, “Non-pneumatic tire and rim combination,” (Steinke, et. al.)), the contents of both of these patents hereby incorporated by reference. The shortcomings of this system are weight and fixed tire stiffness.
The present invention describes a novel way of combining the benefits of variable tire stiffness with a damage tolerant tire design.